MAO-B inhibitors may have weaker symptomatic effects than levodopa and dopamine agonists
in early Parkinson’s disease. They may reduce the rate of motor fluctuations
compared with initial levodopa therapy and may have fewer significant adverse effects
than the older agonists.

A Cochrane review «»1«Caslake R, Macleod A, Ives N, Stowe R, Counsell C....»1 included 2 studies with a total of 593 patients with idiopathic Parkinson’s
disease. Both trials compared selegiline with a dopamine agonist (bromocriptine or
lisuride), whilst one also compared selegiline with levodopa. The median follow-up
was 20 months in the other and 36 months in another trial. MAO-B inhibitors were not
associated with a significant increase or decrease in deaths compared with levodopa
(odds ratio (OR) 0.96; 95% CI 0.52 to 1.76) or dopamine agonists (OR 1.30; 95% CI
0.69 to 2.45). Those receiving MAO-B inhibitors were more likely to require add-on
therapy during
follow-up than those receiving levodopa (OR 12.02; 95% CI 6.78 to 21.31) or dopamine
agonist (OR 2.00; 95% CI 1.05 to 3.81). There was a reduction in motor fluctuations
with MAO-B inhibitors compared with levodopa (OR 0.55; 95% CI 0.32 to 0.94) but not
dopamine agonists (OR 1.15; 95% CI 0.65 to 2.05). Withdrawals due to adverse events
were less common with MAO-B inhibitors than with dopamine agonists (OR 0.11; 95% CI
0.01 to 0.99).

Comment: The quality of evidence is downgraded by study quality (lack of blinding, more than
20% loss of follow-up in larger trial) and indirectness (comparison made with older
dopamine agonists than currently used).